About

John M. Vohs holds a Bachelor of Science Degree in Chemical Engineering from the University of Illinois and a Ph.D. in Chemical Engineering from the University of Delaware. He joined the faculty at the University of Pennsylvania in 1989 and is currently the Carl V. S. Patterson Professor of Chemical Engineering. His research interests encompass surface science, catalysis, photocatalysis, and solid-state electrochemistry. His group specializes in elucidating structure-activity relationships for catalytic materials, including metals and metal oxides, and in developing anodes and cathodes for solid oxide fuel cells and electrolyzers. The overarching theme of his research is understanding the relationships between the local atomic structure of surfaces and their catalytic and electrocatalytic activity, with a focus on advancing more efficient and renewable energy sources. Current projects include using atomic layer deposition to grow functional oxide films on high surface area supports, designing metal and metal oxide sites in mesoporous materials, tailoring surface catalytic properties of fuel cell electrodes, and studying catalytic routes for upcycling waste polymers into higher value products.

Research topics

• Chemistry
• Nanotechnology
• Materials science
• Metallurgy
• Chemical engineering
• Physical chemistry
• Organic chemistry
• Geology

Selected publications

• The Effect of TungstenOxide Supports on Pt, Pd, and Ru Catalysts

  SSRN Electronic Journal · 2026-01-01

  preprintOpen accessSenior author
  PublisherDOI

• The effect of tungsten-oxide supports on Pt, Pd, and Ru catalysts

  Molecular Catalysis · 2026-04-08

  articleOpen accessSenior authorCorresponding

  • The catalytic effects of a WO x overlayer depend on the metal identity. • WO x forms overlayer on metal nanoparticles and suppresses gas adsorption. • Pt and Pd on WO x /Al 2 O 3 show less activity loss than adsorption experiments suggest. • Competitive reactant adsorption could displace WO x , reducing Pt and Pd activity. • Strong WO x binding deactivates Ru, preventing reactants from accessing Ru sites. The catalytic properties of Pt, Pd, and Ru supported on thin WO x films were compared to their γ-Al 2 O 3 -supported counterparts in order to understand the role of WO x as a support. The catalysts were prepared by vapor deposition of Pt, Pd, or Ru onto either γ-Al 2 O 3 or 0.5-nm-thick WO x films deposited onto the γ-Al 2 O 3 by Atomic Layer Deposition (ALD). Following reduction at 573 K, CO adsorption was completely suppressed on each of the WO x /γ-Al 2 O 3 -supported metals and could not be restored by high temperature oxidation. For Pd and Pt, rate constants for cyclohexane dehydrogenation and toluene hydrogenation were modestly lower on WO x /γ-Al 2 O 3 than on γ-Al 2 O 3 , even though CO adsorption was suppressed. It is hypothesized that the high activity of the WO x /γ-Al 2 O 3 -supported metals is due to reactant molecules competing with mobile WO x overlayers to access metal sites. For Ru, cyclohexane dehydrogenation, toluene hydrogenation, and n-hexane hydrogenolysis were completely poisoned when WO x /γ-Al 2 O 3 was used as the support. DFT calculations indicate that WO x binds much more strongly to Ru compared to Pt and Pd, explaining why reactants cannot access Ru sites on Ru/WO x /γ-Al 2 O 3 .

  PublisherDOI

• Pyrolytic Transformations and Kinetic Stabilization of Heteroatom Configurations in Nitrogen-Doped Carbon Electrocatalysts

  ACS Nano · 2025-11-14 · 2 citations

  article

  Heteroatom-doped carbons are considered promising earth-abundant alternatives to traditional materials for electrochemical energy conversion and storage, with the N-doped carbons being the most widely studied. The heteroatom dopants, synthesized through pyrolysis, typically exhibit a mixture of configurations. This, combined with our limited understanding of how dopant configurations are determined and controlled, has hindered both fundamental and practical advancements in this area. Here, we elucidate the pyrolytic formation of N functionalities in nitrogen-doped carbons. This was accomplished using model platforms in which precursor molecules, containing either pyridinic, pyrrolic, or graphitic N, were uniformly adsorbed from the vapor phase onto preexisting carbon black. Tracking the pyrolysis of all three platforms revealed that the thermodynamically favorable state is characterized by a mixture of pyridinic, pyrrolic, and graphitic N functionalities. Achieving complete specificity in N configuration requires kinetically stabilizing the N states derived from the precursor. Furthermore, the transformation between pyrrolic and graphitic N is mediated by pyridinic N. The CO2 electroconversion activity of individual N functionalities was evaluated with N-doped carbons containing exclusively pyridinic, pyrrolic, or graphitic N. We found that the intrinsic activity for the electrochemical CO2 reduction reaction follows the pyrrolic > pyridinic > graphitic order on a per N basis. This study provides essential insights into the precision synthesis and design of heteroatom-doped carbons.

  PublisherDOI

• Single Metal Atom Catalysts Prepared by Diluted Atomic Layer Deposition

  ACS Applied Materials & Interfaces · 2025-08-15 · 5 citations

  articleSenior authorCorresponding

  The scalable and facile preparation of single-atom catalysts remains a critical challenge. Here, we introduce diluted atomic layer deposition (DALD), a unique approach for synthesizing supported metal catalysts with precisely tunable loadings. Unlike conventional metal deposition by ALD which uses pure metal precursors, DALD employs a diluted precursor mixture, combining organometallic precursors with the corresponding free ligand in controlled ratios. The method enables precise control over metal loadings, allowing the synthesis of structures ranging from nanoparticles to isolated single atoms, as exemplified by Ir, Rh, and Pt on high-surface-area γ-Al2O3. With its inherent simplicity and exceptional efficiency in metal precursor utilization, DALD represents a highly scalable strategy, unlocking opportunities for integrating single-atom catalysts into industrial processes.

  PublisherDOI

• Oxidation of n-alkanes using TS-1 and H2O2: Effects of chain length and solvents

  Applied Catalysis A General · 2025-05-27 · 1 citations

  articleOpen accessSenior authorCorresponding

  The selective oxidation of n-C 8 H 18 , n-C 12 H 26 , n-C 16 H 34 , n-C 20 H 42 , and n-C 36 H 74 was studied with a goal of using these as models to provide insight into how to functionalize polyolefins. Reactions were carried out using a TS-1 catalyst and H 2 O 2 in a batch reactor with different cosolvents, including methanol, acetone, acetonitrile, methyl ethyl ketone, and methyl butyl ketone. Rates decreased with increasing alkane size, possibly due to the reduced solubility of larger alkanes into the water-rich phases. Cosolvents that promote the partitioning of alkanes in the aqueous phase increased the rates. 1 H NMR spectroscopy demonstrated that ketones were the primary products, although some alcohols also formed. There was preferential reaction at the 2 position in the alkanes, but reaction at central carbons was also observed. The results of this study suggest strategies for using this catalytic chemistry to functionalize polyolefins. • The oxidation of alkanes with varying sizes was investigated using TS-1 and H2O2. • Alkane chain lengths and solvents significantly influence oxidation activity. • Alkane partitioning plays a key role in the reaction. • Oxidation preferentially occurs on the second carbon of alkanes.

  PublisherDOI

• Evidence for the mobility of tungsten oxide overlayers on supported Pt catalysts

  Applied Catalysis B: Environmental · 2025-09-16 · 1 citations

  articleSenior authorCorresponding
  PublisherDOI

• Redistribution of Ru in Fe₂O₃–Ru Nanocatalysts through an Oxidative Pretreatment Improves Reverse Water–Gas Shift Activity

  ACS Applied Nano Materials · 2025-07-24

  article

  We have synthesized Fe–Ru nanoparticles via a solvothermal method to create catalysts for the reverse water–gas shift reaction and demonstrated the impact of reductive and oxidative pretreatments on both catalytic performance and structure. Catalytic testing showed improved activity after exposure to O2 at 600 °C. In contrast, the activity became lower if then exposed to H2 at 600 °C. Environmental scanning transmission electron microscopy and scanning electron microscopy showed that exposure to O2 at 600 °C changes the morphology and completely oxidizes Fe into Fe2O3. Exposure to H2 at elevated temperature caused Ru coalescence at the surface of the nanoparticle, forming clusters which decreased the optimization of Ru. Reoxidation of the particles exposed to H2, however, caused a redistribution of Ru that appears beneficial in maximizing Ru exposure and synergy with Fe oxide, with no major changes in the morphology and oxide structure. Our diagnostics demonstrate the complex and reversible rearrangements possible in these multicomponent particles and the benefits of oxidative pretreatment to enhance or regenerate Fe–Ru catalysts in other important catalytic reactions such as Fischer–Tropsch synthesis.

  PublisherDOI

• Investigating polymer infiltration kinetics in nanoporous metal scaffolds using UV-vis spectroscopy

  Soft Matter · 2025-01-01

  articleOpen access

  spectroscopic ellipsometer results. AFM and XPS support the strong attraction of P2VP for the Au surface and pores as demonstrated by wetting of P2VP over surface ligaments and a shift of the 4f orbital from the N on P2VP to higher binding energy, respectively. Using nanorods configured as a "T" to model ligament geometry, discrete dipole approximation (DDA) simulations capture the optical properties of the P2VP/NPG nanocomposite during infiltration and confirm experimental results. The evolution of the P2VP/NPG optical properties is attributed mainly to an increase in the effective refractive index within the pores. This study presents UV-vis spectroscopy as an alternative method for studying polymer infiltration into nanoporous metal scaffold films.

  PublisherOA PDFDOI

• Enhanced Methane Steam Reforming Over Ni/BaZrO3

  Catalysis Letters · 2025-06-21 · 1 citations

  articleOpen accessSenior author

  Abstract Thin films of BaZrO 3 , 0.5- and 1.0-nm thick, were prepared on high-surface-area MgAl 2 O 4 (MAO) by Atomic Layer Deposition (ALD) and examined as supports for Ni catalysts in Methane Steam Reforming (MSR). Scanning Transmission Electron Microscopy (STEM) showed that the films were conformal with the MAO surface. X-Ray Diffraction (XRD) with Rietveld Analysis indicated that the 1.0-nm film had a perovskite structure. A catalyst with 1-wt% Ni on the BaZrO 3 /MAO support exhibited similarities to exsolution catalysts in that catalysts oxidized at 1073 K and reduced at only 773 K were nearly 4 orders of magnitude less active than catalysts oxidized and reduced at 1073 K. Rates on Ni/BaZrO 3 /MAO catalyst were higher than those on Ni/MAO and exhibited a significantly different activation energy. Because BaZrO 3 is a proton conductor, it is suggested that MSR rates on Ni/BaZrO 3 /MAO are enhanced by proton transfer at the Ni-perovskite interface. Graphical Abstract

  PublisherOA PDFDOI

• Synthesis of Thin-Film Cumn2o4 for Low-Temperature Co Oxidation

  SSRN Electronic Journal · 2024-01-01

  preprintOpen access1st authorCorresponding
  PublisherDOI

Recent grants

• UNS: Mechanistic Studies of Hydrodeoxygenation of Lignin-Derived Aromatic Oxygenates over Bimetallic Catalysts

  NSF · $330k · 2015–2020

• Collaborative Research: DMREF: Atomically precise catalyst design for selective bond activation

  NSF · $538k · 2023–2027

• Thermodynamic Measurements of Redox Properties of Supported Oxide Catalysts

  NSF · $300k · 2006–2010

• Materials World Network: Tailoring Electrocatalytic Materials by Controlled Surface Exsolution

  NSF · $400k · 2012–2016

Frequent coauthors

• Raymond J. Gorte

  266 shared

• Mark A. Barteau

  Texas A&M University

  41 shared

• John T. S. Irvine

  26 shared

• Tae-Sik Oh

  25 shared

• Rainer Küngas

  23 shared

• Abhaya K. Datye

  23 shared

• Yong Wang

  22 shared

• Guntae Kim

  22 shared

Labs

• Vohs Research GroupPI

Education

• Ph.D., Marketing

  University of Minnesota

  2003

• M.S., Marketing

  University of Minnesota

  1999

• B.A., Psychology

  University of Minnesota

  1997

Awards & honors

• 2014 George H. Heilmeier Faculty Award for Excellence in Res…
• 2007 Philadelphia Catalysis Club Award
• 2002 Carl V.S. Patterson Professorship of Chemical Engineeri…
• 1997 Union Carbide Research Innovation Award
• 1996 Union Carbide Research Innovation Award